Eyelids are the part of the eyes. Its main purpose is to cover and protect the eyes by closing or blinking. It keeps the cornea moist.
Also, it protects the eye from too much intense light or injury and high heat sources. The other necessary function of it is the lubrication of the eyes. It helps to maintain the structural integrity of the eyeball. In Latin, it is known as Palpebra.
Definition of Eyelids
They are the folds that cover the eyeball front or it is the movable folds of skin and muscles that can be closed over the eyeball.
Function of Eyelids
Eyelids are essential for sufficient tear film distribution across the ocular surface, tear drainage, protection of the ocular surface, and cosmesis.
Also, it contains glands that exude substances responsible for lubricating the ocular surface and protecting the eyes from dust particles. It closes to keep insensitive light and harmful objects outer and keep moisture in the eyes.
Etymology of Eyelids
The word eyelid originates from the Middle English eye-led, eiȝelid, eghe-lydd, yȝe-lydd, ehlid, yhelidd equivalent to eye + lid.
Similar Words
- Lid
- Palpebra
- Nictitating Membrane
Synonyms of Eyelids
- Cilium
- Optic
- Eye protector
- Protective Fold
- Oculus Organ
- Blinker
Antonyms of Eyelids
- Untie
- Effector
- Inattention
Upper Eyelid
It covers the majority of the cornea. It blinks at a normal rate of approximately 15 times per minute. Only one part of these blink reflexes covers up the whole cornea. Also, it has the levator palpebrae superioris muscle that originates from the depths of the orbit over the dorsal rectus muscle.
Lower Eyelid
It contains very thin skin, a small tarsal plate, and muscles that open and close the eyelid. This eyelid begins from the eye and expands to the joint of the skin of the cheeks. It works to depress the eyelid in downgaze and maintains the straight position of the tarsal plate.
Double Eyelid
It is an eyelid with a fold or a crease on the upper lid. In Asian cultures, double eyelids are associated with beauty.
Almost 50% of the Asian population has a minimum double eyelid. The surgery for double eyelids has become an admired and trendy cosmetic surgery amongst people in China, Korea, Singapore, Asian Americans, and many more.
Swollen Eyelids
It is a symptom and is a very common issue. The thickness of the skin of the lid is less than 1mm. The eyelid is capable of swelling much as its tissues are loose and stretchy. The cause of the swollen eyelid is:
- Orbital Cellulitis
- Chalazion
- Style
- Infection
- Injury
- Inflammation
- Allergy
Structure of the Eyelid
Layers:
Eyelids are made up of several layers from superficial to deep some of which are mentioned below:
Skin:
The outer layer of the eyelid is the skin. Its features are not different from skin on the rest of the body with the possible exemption of large pigment cells, somewhere else but are much more in the skin of the eyelids.
The cells can wander and it is these movements of the pigment cells that determine the changes in coloration seen in some people with changes in health. The skin has sweat glands and hairs. As the connection between skin and conjunctiva is approached, the hairs change their character to become eyelashes.
Subcutaneous Tissue
It is also known as hypodermis. It comprises larger blood vessels and nerves. In this layer, such types of cells are found which are given below:
- Fibroblasts Cells
- Macrophages Cells
- Adipose Cells
Orbicularis Oculi
This is derived from the medical orbital edge, medical palpebral ligament and the lacrimal bone. Then, it is put into the skin about the margin of the orbit and the superior and lower tarsal plates. It has three parts which are given below:
Palpebral Part: It gently closes the eyelids.
Lacrimal Part: It involves the drainage of tears.
Orbital Part: It tightly closes the eyelids.
Orbital Septum
It is a thin and fibrous membrane that acts as a frontal boundary of the orbit. It starts from the orbital rim. This expands to the tarsal plates of the lids. It combines with the ligament of the Levator Palpebrae Superioris in the superior eyelid. It extends with the tarsal plate in the inferior lid.
Tarsal Plates
These plates are in the palpebral region of the orbicularis oculi muscle. It has two parts which are the superior tarsus upper eyelid and inferior tarsus. They work to form the scaffolding of the eyelid. It is composed of dense connective tissue.
Also, Meibomian glands lie in these plates. This is a particular kind of sebaceous gland that obscures oily substances onto the eye to slow the evaporation of the tear film of the eyes. Also, it prevents the eyelids from sticking to one another when closed.
Conjunctiva
It is a thin mucous membrane. It lines the inside of the eyelids. This covers the sclera. It is extremely vascularized with a lot of microvessels which is accessible for visualizing studies. It comprises of:
- Non-Keratinized
- Stratified Squamous Epithelium with Glass Cells
- Stratified Columnar Epithelium
- Stratified Cuboidal Epithelium
The parts of the conjunctiva are given below:
Palpebral or Tarsal Conjunctiva: It lines the eyelids.
Bulbar or Ocular Conjunctiva: It covers the eyeball. The average thickness of this membrane is almost 33 microns. This part of the conjunctiva is tightly bound to the underlying sclera by the capsule of the tenons.
Fornix Conjunctiva: This part forms the connection between the bulbar and the palpebral conjunctivas. It is loose and flexible or stretchy. It permits the movement of the eyelids.
General Disorders of Eyelids
- Chalazion
- Ectropion
- Blepharitis
- Trichiasis
- Blepharospasm
- Ptosis
- Xanthelasma
- Actinic Keratosis
- Eyelid Swelling
- Dry Eye
- Facial Palsy
- Nevus
- Hidrocystoma
- Coloboma
- Hordeolum
- Floater
- Glaucoma
- Baggy Eyelids
Examples
- His eyelids closed gradually.
- Sara lifted her eyelid to see what Ali was doing.
- Ahmad watched her with half-closed eyelids.
- Every eyelid comprises of a fibrous plate
- Sana’s eyelids grew heavier.
FAQs (Frequently Asked Questions)
Mention the most common types of double eyelids.
- Monolid
- Partial Eyelid Crease
- Multiple Creases
- Tapered Eyelids
- Parallel Eyelid Crease
Which are the 2 types of eyelids?
- Monolids Eyelids
- Double Eyelids
Mention the points of the eyelids.
There are 2 points of the eyelids which inner aspect is known as the medial canthus while the outer aspect is known as the lateral canthus.
What are lids made up of?
- Skin
- Subcutaneous Tissue
- Orbicularis Oculi Muscle
- Submuscular Areolar Tissue
- Fibrous Layer
- Lid Retractors
- Fat Pads
- Conjunctiva
Which kind of eyelid is considered beautiful?
Double Eyelids are the most beautiful.